# The Magic and Mystery of π (Pi)

Baylor mathematics chair Dorina Mitrea, Ph.D., explains what makes Pi important.

**Contact: ****Kelly Craine****, Baylor University Media & Public Relations, 254-297-9065***Follow us on Twitter: ***@BaylorUMedia**

WACO, Texas (March 12, 2024) – Described as beautiful, elusive and enigmatic, Pi has fascinated and inspired mathematicians throughout history. So beloved, the mathematical equation even has its own holiday. Started by physicist Larry Shaw in 1988 as a fun day for his staff at San Francisco’s Exploratorium science museum, March 14 was officially declared National Pi Day in 2009 by the U.S. Congress.

Deceptively simple, Pi is the ratio of the circumference of a circle to its diameter, calculated by dividing the length of the diameter of a circle into its circumference. The miraculous fact about Pi is that no matter the size of the circle, the value does not change, making Pi a mathematical constant. Adding to its allure, Pi is also an irrational number with no end and no repeating digits.

**Dorina Mitrea, Ph.D.**, professor and chair of the **Department of Mathematics** at Baylor University, explains Pi’s uniqueness it this way: “4,000 years ago, people realized the existence of the special number, which had a very clear relevance to what they were doing on a daily basis, and that has not changed.”

**History of Pi**

The earliest use of Pi was documented 4,000 years ago in Babylon and was probably used for construction. According to Mitrea, despite this discovery, the approximate value for the ratio itself continued to elude people. “It turned out that it wasn’t easy to actually give a number that represents exactly that ratio.”

In 250 B.C.E., Greek mathematician Archimedes created the first algorithm that calculated the first few decimals in Pi. He drew hexagons inside and outside of a circle. Then he doubled the number until reaching a 96-sided polygon. With this algorithm, Archimedes was able to determine 3.14 as the first decimal points of Pi. This breakthrough would begin the never-ending calculations of the never-ending number.

As calculations grew, there was a need to write Pi more accurately since the numeral form of Pi doesn’t fully express its accuracy.

“Although it is impossible to write out all the digits for Pi, from a mathematical point of view, it is a clear, well-defined number,” Mitrea said. In 1709, mathematicians solved the issue by using the Greek letter π to represent the never-ending number.

Only the first 40 digits (3.1415926535897932384626433832795028841971) are needed to perform accurate calculations, yet to this day mathematicians continue to expand the numbers. Through modern computing technology, Pi was calculated to a record 100 trillion digits in 2022.

**Relevance of Pi**

More than just a geometry formula, the practical uses of Pi can be found everywhere. Scientists use Pi to understand anything that involves a circle, sphere or curve. Whether calculating the vastness of space or understanding the spiral of DNA, Pi is involved.

“As soon as you start working on problems, immediately you have to resort to Pi,” Mitrea said. “That’s why it will continue to be relevant. You can’t do anything without this special number.”

**Cultural influence of Pi **

The mathematical constant’s popularity has transformed it beyond the scientific world into a pop culture icon. Pi has been the subject of numerous documentaries and books. World-renowned astronomer Carl Sagan mused in his 1985 novel “Contact” that a message from the creator of the Universe is embedded within Pi.

Pi was famously featured in the 1967 Star Trek episode “The Wolf in the Fold,” where Mr. Spock stops a murderous computer by instructing it to compute the last digit for the value of Pi – an impossible task that destroyed the computer.

Competitions are held to determine who can recite the most digits of Pi. Known as piphilology, the world record is held by Thomas W. Ferguson, who recited Pi to 3,142,958 decimal places in 2006.

**Future of Pi**

The possibilities of what Pi can do are infinite at the number itself. Mathematicians continue to be excited about the mystery of Pi and its secrets.

“Through constant reasoning and questioning of what else can we say about Pi, we learn more about it,” Mitrea said. “Even now there are many other mathematical questions that are open. It never stops amazing us.”

**Celebrate Pi Day**

As Pi Day on March 14 approaches, there are many ways you can celebrate the wonder of Pi.

- Enjoy some Pi-themed food. Pizza pie, chicken pot pie or cherry pie all are options.
- Take a walk for 3.14 miles.
- Contemplate the beauty of the natural world and how Pi is part of it.

**About Dorina Mitrea**

Dorina Mitrea, chair of the Department of Mathematics and professor of mathematics, was recognized recently as a 2024 Fellow of the American Mathematical Society, one of only four mathematicians from Baylor to be honored with the prestigious designation. Marius Mitrea also serves as professor of mathematics, with numerous research areas in partial differential equations, harmonic and Fourier analysis, geometric measure theory, complex and Clifford analysis, spectral theory, differential geometry, semigroup theory, and functional analysis.

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